One Model, Many Materials: Understanding Multi-Material Structural Design with Integrated Design Tools

Modern building design is increasingly defined by hybrid systems. Engineers are combining multiple building materials within a single structure to meet demands for efficiency, constructability, and performance.

This approach allows each material to be used where it performs best, but it also introduces a level of complexity. Coordinating different material behaviors within one structural system and load path is no longer a niche challenge. It is becoming standard practice.

What is Multi-Material Structural Design

Multi-material structural design is the practice of using different building materials in one coordinated structural system so that load paths, stiffness, and movement are all working together.

In real projects, this shows up as:

• Mass timber framing on top of a concrete podium
• Steel transfer beams carrying concrete slabs above
• Masonry cores tied into wood gravity framing

These systems are now common in commercial and residential projects, especially as teams look for more sustainable and efficient buildings.

Why Multi-Material Design Matters

Using multiple materials allows engineers to fine-tune structural systems and capitalize on the best attributes of each material. Multi-material structural systems help you:

• Provide stiffness where you need it, such as at a concrete core
• Allow for long spans and complex geometries by utilizing steel framing
• Reduce weight and improve sustainability through the use of mass timber or wood framing

The result can be an efficient structure, but only if the different materials and components work together as intended.

What are the Challenges in Multi-Material Design

Designing with multiple materials is not just about checking individual members. It is about managing how different materials behave together for a cohesive structural system.

• Different stiffness and load paths

  Load flows through buildings based on the relative stiffness of its members. A stiff concrete wall will attract more load than a flexible wood shear wall. If the varying stiffnesses are not properly accounted for in the design, the assumed load paths can lead to overstressed elements or inefficient designs.

• Differential movement

  Materials respond differently to load, temperature, and time-dependent effects. For example, wood shrinkage and concrete creep can introduce movement that must be accommodated at the interface between members. Without careful coordination, this can lead to serviceability issues or unintended force transfer at connections.

• Material-specific design requirements

  Each material follows its own design code and detailing requirements. Engineers must verify that every component satisfies its governing criteria while still functioning as part of a unified system. This means tracking multiple code provisions and detailing rules within one structural model.

• Conflicting definitions of optimization

  The definition of an optimized design is not consistent across materials.  Steel and wood designs are optimized through member sizing and spacing while concrete and masonry designs may keep geometry fixed while optimizing with the reinforcement layout. Balancing these differing approaches requires iteration across the entire system.

Why Workflow Fragmentation Adds Complexity to Design

Beyond engineering theory, one of the biggest obstacles in multi-material designs is workflow.

Many engineers still rely on a mix of tools for each material type such as a vetted spreadsheet for masonry walls, a standalone model for wood trusses, and a 3D model for steel frames. While each tool may be effective on its own, the overall process becomes fragmented.

This fragmentation creates several problems:

• The load path is difficult to determine based on relative stiffness of different materials
• Geometry and loading must be updated in multiple locations
• Changes are difficult to track across models
• Manual data transfer introduces risk of error
• Iteration becomes slower and more cumbersome

In multi-material design, coordination is critical and these inefficiencies compound quickly.

How Integrated Software Reduces Friction

An integrated workflow addresses these challenges by keeping analysis and design all in one file. Structural analysis software should support multi-material structural modeling without requiring you to rebuild the project in multiple tools.

RISA’s product ecosystem is built around this idea. It allows engineers to design across multiple materials without breaking the workflow.

• Clear load path calculations

  RISA-3D utilizes the actual stiffness of the structure to determine the load path. This removes much of the guesswork from an engineer’s calculations and leads to a more efficient structural system. Engineers can place the lateral stiffness where it is needed and reduce overdesign in redundant load paths.

• Specialized tools that still work together

  Programs like RISAFloor, RISA-3D, and RISAFoundation each focus on a specific aspect of the design - gravity systems, lateral systems, and foundations - while maintaining direct integration. Engineers can use the right tool for each task without losing continuity.

• Direct model and load transfer

  Instead of recreating models or manually copying loads, data automatically transfers directly between programs as updates are made to the model. This ensures that geometry, loading, and member forces remain consistent throughout the design process and across all materials.

• Standard interface and workflow

  A shared interface across RISA products reduces the learning curve and makes it easier to move between different parts of the design.

• Unified reporting across materials

  Results for all material types can be captured within a coordinated report in each program. This simplifies calculation packages, reduces administrative time, and improves traceability during review.

• Material-specific design within one system

  Each material can still be designed according to its own code, design methodology, and optimization logic, within a single coordinated model. This allows engineers to maintain precision and code compliance without sacrificing efficiency. 

How the RISA Workflow Provides Engineers an Advantage for Multi-Material Designs

As multi-material systems become the norm, your ability to coordinate multiple materials accurately and efficiently will be a key differentiator for your firm.

An integrated RISA workflow helps you:

• Minimize redundant modeling and manual data transfer
• Keep load paths and material behaviors coordinated
• Reduce the risk of mismatched assumptions or input errors
• Iterate faster on design choices and optimizations
• Deliver clearer, more defensible calculation packages

RISA’s approach enables engineers to maintain a single, coordinated structural model while still leveraging specialized tools for each material. The result is a more efficient design process, improved accuracy, and greater confidence that the structure will perform as intended.